Philips has announced that it will be auctioning the legendary “Bao Dai” Rolex reference 6062 at its upcoming Geneva sale on May 13 and May 14 (with pre-sale preview on May 11). The “Bao Dai” is one of the “most valuable and desirable Rolexes” with the “most complicated and iconic Oyster-cased model” ever made, according to the luxury Swiss watch manufacturer. Not only does the timepiece have a pre-sale estimation of over $1.5 million USD, but the rarity and imperial provenance — it was owned by the last emperor of Vietnam, Bảo Đại, during 1954 — increases its allure.

The triple calendar Rolex features moonphase in yellow gold, and is one of the three black dial models known to exist with diamond markers, and the only one to feature diamond markers at even hours. The last time the timepiece was sold was in 2002 for what was then the most expensive Rolex ever sold at auction.